A chiller is a component of an air-conditioning system that can be used to cool the air in a room. One or more pumps, which may or may not be integral to the chiller, circulate a working fluid, such as water, in a chilled-fluid loop from an air handler to an evaporator. In the air handler, the working fluid can extract heat from air in the room to be cooled. In the evaporator, the heat that was picked up by the working fluid in the air handler is then transferred from the working fluid to the colder refrigerant fluid in the refrigeration loop.
In one variety of chillers, the refrigeration loop that cools the chilled-fluid loop is a compression direct-expansion refrigeration circuit. This refrigeration loop includes, in addition to the evaporator, a compressor, a condenser and an expansion mechanism. The refrigerant fluid absorbs heat from the working fluid in the evaporator, where the refrigerant fluid is vaporized, and then dumps that heat in the condenser as the vaporized refrigerant fluid is re-condensed.
The chiller typically includes four main types of power-consuming components, including compressors, chilled-water circulating pumps, a controller, and condenser fans. All of these components are typically fed from a common point of power application to the chiller. When power is lost to the chiller, the operation of each of these components thereby ceases, resulting in a prompt loss of heat-removal capacity from the building or equipment being cooled.
In one application, chillers are used to cool computer rooms, where computer components can generate substantial operational heat. By removing this heat, a desired room temperature can be maintained to thereby help ensure that the computer components therein do not overheat. Generators are sometimes employed to allow continued operation of the chiller during a power loss.